Induced-draft device



E. PRAT.

INDUCED DRAFT DEVICE.

AFPLICATION FILED APR. 2, I920.

Pammbed 00%. 31, 1922.

mm sm Patented Get. 151, 1922. i Ti-941 13 333 STATES EMILE PRAT, F PARIS, FRANCE, ASSIGNOR 'I'O SOCIETE DES CHEIVIINEES LOUIS FEAT A TIRAGE IND'UIT, OF PARIS, FRANCE.

INDUCED-DRAFT DEVICE.

Application filed April 2, 1920. Serial No. 370,860.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L, 1313.)

T 0 all whom it may concern. Fig. 2 is a plan view of the same.

Be itknown that I, EMILE PRAT, citizen Fig. 3 is a fragmentary elevation similar of the French Republic, residing at Paris, to Figure 1 with the rings arranged in nest- France, 64 Rue de Miromesnihhave invented ing relation but spaced above the fan cas- 5 certain new and useful Improvements in mg.

Induced-Draft- Devices (for which I have Fig. 4 is a similarview showing the rings filed application in France, January 10, fully extended, and i 1918), of which the following is a specifica- Fig. 5 is a sim lar view showing the rings tion. 1n another position.

10 Induced-draft for furnaces, produced by 1 is the flue through which the gasesare an ejector such as generally employed, condischarged into the chimney; 2 is the sheetsists more particularly in the combination iron chimney; 8 is the fan, which is arranged 65 of an externally arranged fan and an ejecentirely within the chimney, and is prefertor chimney, the two apparatus cooperating ably provided with two intakes. Its exter- 15 for the discharge of the smoke, gas, vapours nal form is that of a solid body which offers and the like. the least practicable resistance to the pas- This system of draft, which has lately been sage of the gases, so that its presence in extensively employed, compares favorably, the chimney does not cause any appreciable as a rule, with the induced-draft system conloss, either through contraction or expan- 20 sisting of an ordinary chimney, and of a sion, as regards the gases circulating fan through which all the gases to be disround it. charged are passed. The fan delivers into a short nozzle 4,

These two systems have the defect of low about which are arranged one or more exetliciency because the gases have to take a 1.')ansion-rings5,5 and 5 for varying the sec- 25 sinuous course, and because said gases can-. tional area of the ejector nozzle. These rings not be so regulated as to economize in fuel are tapered outwardly and their lower ends consumption owing to the fact that the speed preferably taper in the opposite direction in of the fan cannot usually be modified. order to facilitate the passage of the gases The object of the present invention is to between them. Around the nozzle 4 is ar- 30 lessen these drawbacks, and the invention is ranged an auxiliary steam device 6, in the characterized by the fact that the fan is shape of a ring having a circular series of situated inside the chimney and has the exsteam outlet ports, the discharge of steam ternal form of a solid offering the least pracfrom which may be manually controlled by ticable resistance to the flow of the gases; means of the valve 7 the arrangement as a 35 that is to say, the body of the fan is rounded whole affording capability for effecting at its lower sides while its delivery passage staged expansion of the steam. is upwardly tapered. In one form of the The expansion rings 5, 5, 5 when disinvention, the delivery nozzle of the fan is placed vertically, as shown in F 4, by surrounded by one or more so-called expanmeans of chains 9 passing over pulleys 8, or

40 sion-rings which are movable axially so as by any other means, vary the sectional area to vary the sectional area of the nozzle of the of the ejector nozzle and consequently the fan. The device may be completed by an ejecting action of the fan. Thus when, as in auxiliary steam jet, in the shape of a ring, in Figure 3, all the rings are collapsed, the sec combination with staged expansion. tional area of the discharge orifice of the fan 45 The invention is described hereinafter with is reduced to a minimum, whereas when, as

reference to the accompanying drawing, in Figure 4, they are drawn out like a telewhich illustrates, diagrammatically and by scope, they give a maximum sectional area way of example, one method of carrying out of blast. the invention. I It should be noted that the position of 50 Figure 1 is a vertical diagrammatic secmaximum sectional area of blast corresponds tion of the induced draft chimney showing to minimum work of the ejector, nearly the all the rings in the lowermost position and whole of the gases passing through the fan. in nesting relation. Practical experience has shown that, for

a given consumption, steam delivered througha multiple jet arranged as a ring gives better results than delivery through a single aperture. The auxiliary steam de vice is therefore arranged in the form of a multiple-jet ring 6 surrounding the nozzle 4, but with this peculiarity, that the expansion of the steam can be staged by means of the rings 5, 5 5* so as to increase the efliciency of the device (Figure 5).

It will be understood that the samearrangement for regulating withrings may also be applied to the nozzles of fans mounted outside the chimney, as is the case with the majority of existing types.

In my co-pending application Serial No. 370,861, filed April 2, 1920, I have described a draft device in which the fan is always traversed, when working, by all of the gases and in which, when the fan is not working, the gases are carried along by the ejector action of a steam blast. In my co-pending application Serial No. 370,862, filed April 2, 1920, I have further described a draft devicein which a fan divided into two parts simultaneously causes the draft of the combustion gases to the chimney in one part of the fan and blows atmospheric air to the furnace grate in the other part. But my present applicationdoes not relateto any device of the kind as it concerns a draft device in which a portion of the gases passes inside the fan and the remainder outside the fan, means being provided to control the ratio of the two portions.

What I claim is: I

1. A chimney draft device comprising a chimney, a fan arranged to discharge into the chimney, and a plurality of rings arranged about the outlet of said fan for varying the area of said outlet, the uppermost ring being adapted to make close contact with the chimney.

2. A chimney draft device comprising a chimney, a fan arranged to discharge into the chimney, a nozzle at the outletof said fan, a plurality of rings arranged about the outlet nozzle of the fan, and means for raising and collapsing said rings telescopically and for applying the uppermost ring in close contact with the chimney.

3. A chimney draft device comprising a chimney having a convergent part and a divergent part, afan arranged to blow only a portion of the smoke into the chimney, a plurality of divergent rings arranged about the outlet of the fan, and means for raising and collapsing said rings telescopically. and for applying the uppermost ring in close contact with the chimney.

4:. A chimney'draft devicecomprising. an ejector-shaped chimney, a fan arranged wholly inside the chimney, means for drawing only a portion of the smoke through the fan, the remaining portion of the smoke being drawn directly upwardly within the chimney, a plurality of rings arranged about the outlet of the fan, said rings'having oppositely flaring upperand lower portions, andmeans for raising and collapsing said rings telescopically. I

5. A chimney draft device comprising a chimney, a convergent part and a divergent part, a fan arranged wholly within said chimney, said fan having the shape of a solid to present minimum resistance to the flow of gases thereby, a plurality, of divergent rings arranged about the outlet of the fan, and means for raising and collapsing said rings telescopically in variable relative position. y

6. A chimney draft device comprising a chimney, a fan adapted to'discharge into said chimney, a plurality of divergent rings spaced around the fan outlet, means for raising-and collapsing said rings telescopically, and steam ejecting means adapted to eject steam into said rings.

' In testimony whereof I afiix my signature.

- EMILE PRAT. 

